The invention relates to machining and more particularly to improvements in dead centers. Centers are used to support the ends of long workpieces for machining. The work rotates relative to the dead center, creating friction between the parts that can burn both members.
Conventional practice dictates that the operator apply a film of grease or lubricant prior to engaging the center with the work, as lubricant applied with the center engaged is ineffective. The operator must then be vigilant to insure the work and/or center does not overheat from lack of lubrication--stopping the machine periodically to check for binding or burning and, when necessary, backing out and relubricating the center. Such practice wastes time and cannot be regarded as reliable. The problem is at least two centuries old, and is the subject of some early patents.
Industry has successfully circumvented the problem by developing live centers that rotate with the work. Dead centers have, however, a number of advantages over live centers, including higher precision, lower cost and less tool interference, making for easier setups. In addition, they are essentially unaffected by fine grit or swarf, and have the ability to support greater loads.
The current invention offers the inherent advantages over live centers while overcoming the fundamental problem associated with dead centers, and offers additional advantages as well.